Zoom lens system

A zoom lens system, comprising:

• in order from the object side, a positive first lens group and a negative second lens group having a positive plastic lens element;
• and
• means for adjusting a magnification of said zoom lens system by varying a distance between the first and second lens groups, said zoom lens system satisfying the following conditions:
• 0.9<f.sub.t /f.sub.p <1.6 .›.(1).!.
• 0.6<m.sub.p '-m.sub.p <1.2 .›.(2).!.
• .›.2.9<.!. 3.13.ltoreq. m.sub.2 <3.7 .›.(4).!.
• where
• f.sub.t is the focal length of the overall system at the telephoto end;
• f.sub.p is the focal length of the positive plastic lens element;
• m.sub.p is the lateral magnification at the telephoto end of the lens group which includes the positive plastic lens element and which is positioned closer to the image than said positive plastic lens element;
• m.sub.p ' is the lateral magnification at the telephoto end of the lens group which does not include the positive plastic lens element and which is positioned closer to the image than said positive plastic lens element;
• and
• m.sub.2 is the lateral magnification of the second lens group having a maximum magnification at the telephoto end.

A zoom lens system, said zoom lens system consisting of a positive lens group and a negative lens group;

• one of positive lens group and said negative lens group including a positive plastic lens element;
• and
• means for adjusting a magnification of said zoom lens system by varying a distance between said positive lens group and said negative lens group, said zoom lens system satisfying the following conditions:
• 0. 9<f.sub.t /f.sub.p <1.6
• 0.6<m.sub.p '-m.sub.p <1.2
• 2.9<m.sub.MAX <4.0
• where
• f.sub.t is the focal length of the overall system at the telephoto end;
• f.sub.p is the focal length of the positive plastic lens element;
• m.sub.p is the lateral magnification at the telephoto end of the lens group which includes the positive plastic lens element and which is positioned closer to an image than said positive plastic lens element;
• m.sub.p ' is the lateral magnification at the telephoto end of the lens group which does not include the positive plastic lens element and which is positioned closer to the image than said positive plastic lens element;
• and
• m.sub.MAX is the lateral magnification at the telephoto end of the lens group having a maximum magnification.

A zoom lens system, said zoom lens system consisting of, in order from an object side, a positive lens group and a negative lens group having a positive plastic lens element;

• and
• means for adjusting a magnification of said zoom lens system by varying a distance between said positive lens group and said negative lens group, said zoom lens system satisfying the following conditions:
• 0.9<f.sub.t /f.sub.p <1.6
• 0. 6<m.sub.p '-m.sub.p <1.2
• 2.9<m.sub.p '<3.7
• where
• f.sub.t is the focal length of the overall system at the telephoto end;
• f.sub.p is the focal length of the positive plastic lens element;
• m.sub.p is the lateral magnification at the telephoto end of said negative lens croup which includes the positive plastic lens element and which is positioned closer to an image than said positive plastic lens element;
• m.sub.p ' is the lateral magnification at the telephoto end of said positive lens group which does not include the positive plastic lens element and which is positioned closer to the image than said positive plastic lens element;
• and
• m.sub.MAX lateral magnification, at the telephoto end, of said negative lens group having a maximum magnification.